How to generate roll numbers in pandas?

Question

I have the following dataframe.

df = pd.DataFrame({'A':['[email protected]','[email protected]','[email protected]','[email protected]','[email protected]','[email protected]'],
                   'B':[4,5,4,5,5,4],
                   })

I need to generate rollnumber for column A in the format

"string+!--10digitnumberstaringfrom1--+string"

If the values are repeated roll number should be unique.

Expected Output:

              A     B  RollNumber
0   [email protected]    4  ABC000000001AB
1   [email protected]    5  ABC000000002AB
2   [email protected]    4  ABC000000003AB
3   [email protected]    5  ABC000000004AB
4   [email protected]    5  ABC000000002AB
5   [email protected]    4  ABC000000003AB

Can you add expected output and code, what you try? – jezrael Sep 24 '18 at 06:32 — jezrael, Sep 24 '18 at 06:32

jezrael · Accepted Answer · 2018-09-24T06:50:13.487

2

Use list comprehension with zero fill:

#python 3.6+
df['RollNumber'] = [f'ABC{x:010}AB' for x in range(1, len(df) + 1)]
#python 3
#df['RollNumber'] = ['ABC{0:010d}AB'.format(x) for x in range(1, len(df) + 1)]
print (df)

              A  B       RollNumber
0  [email protected]  4  ABC0000000001AB
1  [email protected]  5  ABC0000000002AB
2  [email protected]  4  ABC0000000003AB
3  [email protected]  5  ABC0000000004AB
4   [email protected]  5  ABC0000000005AB
5   [email protected]  4  ABC0000000006AB

EDIT: For same values per column A need factorize with Series.str.zfill:

s = pd.Series(pd.factorize(df['A'])[0] + 1).astype(str).str.zfill(10)
df['RollNumber'] = ('ABC' + s + 'AB')
print (df)
              A  B       RollNumber
0  [email protected]  4  ABC0000000001AB
1  [email protected]  5  ABC0000000002AB
2  [email protected]  4  ABC0000000003AB
3  [email protected]  5  ABC0000000004AB
4  [email protected]  5  ABC0000000002AB
5  [email protected]  4  ABC0000000003AB

edited Sep 24 '18 at 06:50

answered Sep 24 '18 at 06:42

jezrael

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1

@what if I have repeated values check the expected output now – Yog Sep 24 '18 at 06:47
how to use df['RollNumber'] = [f'ABC{x:010}AB' for x in range(1, len(df) + 1)] this code to print from start roll number from 20 – Yog Sep 25 '18 at 12:00
1

@Yog - Use `df['RollNumber'] = [f'ABC{x:010}AB' for x in range(20, len(df) + 21)]` – jezrael Sep 25 '18 at 12:01
geeting this error ValueError: Length of values does not match length of index – Yog Sep 25 '18 at 12:02
1

@Yog - ooops, not tested - need `df['RollNumber'] = [f'ABC{x:010}AB' for x in range(20, len(df) + 20)] ` – jezrael Sep 25 '18 at 12:04
what if df['A'] is not in ascending order ? like `[abc1,abc2,abc4,abc2]` – Pyd Oct 01 '18 at 09:30

How to generate roll numbers in pandas?

1 Answers1